The Tram family of broadcast AM/DRM transmitters by Transradio seem to have
no IMD issues. They make use of adaptive pre distortion and use LDMOS,
however not sure whether Freescale ore NPX hardware but I could find out.
A 10KW unit has just been taken out of business and is on sale by a
broadcast technician responsible for that site before.
http://www.transradio.de/index.php/en/tram-en/am
73
Peter
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Carl
Sent: Dienstag, 2. Dezember 2014 01:02
To: John Kinney; amps@contesting.com
Subject: Re: [Amps] Old Moto RF Decks
BUT, harmonics and IMD are two completely different animals.
Now when is Freescale going to offer a 2-30 or 2-50 mHz device that has high
efficiency and very low IMD at the same time and be targeted at the linear
SSB amp market?
Carl
KM1H
----- Original Message -----
From: "John Kinney" <J.Kinney@freescale.com>
To: "Carl" <km1h@jeremy.qozzy.com>; <amps@contesting.com>
Sent: Monday, December 01, 2014 6:17 PM
Subject: RE: [Amps] Old Moto RF Decks
Hi Carl,
You are correct. I saw very poor IMDs on the two tube version at anything
over about 400 Watts. I friend of mine helped me build a filter, 5 poles as
I recall, for use on the output. It brought the 2nd and 3rd harmonics down
quite nicely, using two tone 1 kHz spacing. We used an Anritsu Spectrum
Analyzer for monitoring into a 2KW dummy load and the 2nd and 3rd harmonics
were down about 50 and 70 db as I recall.
It was a lot of fun playing with those old amps.
Thanks,
John Kinney
RF Solutions Team
Freescale Semiconductor
Tempe, Arizona
(480) 413-4290
KA7CVJ
-----Original Message-----
From: Carl [mailto:km1h@jeremy.qozzy.com]
Sent: Monday, December 01, 2014 1:43 PM
To: Kinney John-R17512; amps@contesting.com
Subject: Re: [Amps] Old Moto RF Decks
SSB IMD goes up rapidly above 300W per tube even with simplistic screen
regulation. Be a good neighbor on the bands with those rather aged and
obsolete designs (1947) that predate widespread SSB use.
Collins rated their 1960 AN/URC-32 at 500W with a pair of lower IMD
4CX250R's at 2000V while Eimac rated them to 2500V with poor IMD specs.
Those transceivers, at 6' tall, ran fine without clobbering other close
channel USN users.
Carl
KM1H
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